Polycystic ovarian syndrome (PCOS) is the most common endocrinopathy and it affects 10 percent of reproductive-aged women. The etiology of chronic hyperandrogenic anovulations, such as PCOS, may have genetic underpinnings. Although the underlying mechanisms are unknown, PCOS is now recognized as hyperandrogenism accompanied by anovulation. Polycystic ovarian morphology is highly correlated with conditions in which the fetus has been exposed to high amounts of sex steroids before birth. For example, women with classical 21-hydroxylase deficiency mimic PCOS, exhibit anovulation, ovarian hyperandrogenism, and LH hypersecretion. Perhaps excess sex steroids early in life may provide a hormonal "insult" that results in manifestation of PCOS later in adulthood. This proposal aims to use a new model, the prenatally-androgenized sheep (long gestation, mono-ovular species), to investigate causal mechanisms for the developmental origins of PCOS. Our preliminary studies indicate that these sheep develop ovulatory defects during adulthood similar to those of women with PCOS: anovulation, elevated LH levels, hyperandrogenemia, hyperinsulinemia, and multifollicular ovaries. In this proposal, we will test the following hypothesis: prenatal exposure to androgens disrupts adult reproductive function culminating in hyperandrogenic anovulation and that this disruption is mediated via reduced sensitivity to the positive feedback actions of estradiol, abnormal gonadotropic drive and/or altered ovarian sensitivity to FSH. The specific Aims of the proposed research are to determine 1) the extent to which fetal exposure to androgens disrupts reproductive cyclicity, ovarian function, ovulatory capacity and fertility in adulthood, (2) if reduced sensitivity to estradiol stimulatory feedback of gonadotropin secretion contributes to the disruptive effects of prenatal- androgenization on postnatal reproductive cyclicity, and (3) if abnormal gonadotropic drive and/or reduced ovarian sensitivity to FSH contributes to the disruptive effects of prenatal- androgenization on postnatal reproductive cyclicity. If our hyposthesis proves to be correct, this would form the basis for a distinct developmental origin of an important reproductive disease in adulthood. Specifically it will establish that discrete, experimentally induced androgen excess of fetal sheep provides the first clear etiology for hyperandrogenic anovulation in adulthood.